Book holder



FIG. 1 is a top, left front perspective view of a book holder showing my new design;

FIG. 2 is a front elevational view;

FIG. 3 is a rear elevational view;

FIG. 4 is a right side elevational view;

FIG. 5 is a left side elevational view;

FIG. 6 is a bottom plan view; and,

FIG. 7 is a top plan view thereof. 

The ornamental design for a book holder, as shown and described. 